1. Field of the Invention
The present invention relates, in general, to an embedded type motorized blind device and, more particularly, to an embedded type motorized blind device which has minimal thickness of a blind incorporating window, which prevents the generation of an overload even in a motor of a large-sized window to be reliably operated and precisely controlled, and which is installed to allow a power supply interruption time to be conveniently and precisely set.
2. Description of the Prior Art
Generally, a blind is a window covering which has horizontal or vertical slats that can be drawn out of the way, often with the angle of the slats adjustable to admit varying amounts of light. From old times, as means for performing the same function as the blind, a reed blind, a sliding screen, a latticework, a shutter, a Venetian blind, etc. have been developed. Recently, a roller shade for rolling a fabric sheet using a spring, a double glazed window unit incorporating a Venetian blind therein, etc. have been disclosed in the art.
In addition to the removably and movably structured blinds, shading devices which are permanently incorporated into buildings have also been disclosed in the art.
While a building has a basic function of isolating an influence from the external environment to some extent, a blind serves as means for rendering a pleasant appearance and decorating natural characteristics of a building.
It has been known that a blind is very advantageous for efficient thermal insulation. This is a result of an air layer formed between the blind and a window.
It is generally required that a blind directly blocks the beams of light and another's gaze, allows some air circulation and an indirect beams of light, ensures visibility from the inside to the outside, and is capable of being removed or moved as occasion demands.
A louver type blind is widely used.
The louver indicates a series of narrow slats which are arranged parallel one to another. By changing an angle of the slats, it is possible to shade the light.
A Venetian blind is most widely used as a blind. In the Venetian blind, horizontal slats painted with a light color and having a curvature are foldably placed behind a window so that they are overlapped in such a way as to be opened or closed to thereby admit varying amounts of light.
These days, motorized blind devices have been disclosed in the art, in which motors are coupled to various blinds to enable automatic control of the blinds. The motorized blind devices are installed in double-glazed window units to be externally and automatically controlled in their operations.
In each of these conventional embedded type motorized blind devices, a raising or lowering amount of the blind and an angle of slats are adjusted using gears, an arithmetic unit, or a timer.
However, the conventional embedded type motorized blind devices suffer from defects in that, when they are installed, it is difficult to precisely set a time for interrupting power supply to a driving unit at uppermost and lowermost positions of the blind in conformity with a varying size of a window, by which an installation time is increased and a skillful person is required.
Also, in the conventional embedded type motorized blind devices, a wound amount of a raising and lowering cord cannot be precisely detected, by which an overload may be applied to a motor to shorten a life span thereof and thereby a wound portion of the cord is likely to be broken.
Further, in the case that the conventional embedded type motorized blind device is incorporated in a large-sized window, since an elongate head box should be installed to extend in a transverse direction, a straightness of a rotating shaft is deteriorated to generate an overload in the motor, by which the motor can be further shortened in its available life span and malfunction of the motor may be caused.
Moreover, because the conventional embedded type motorized blind devices have complicated structures and substantial widths, when they are incorporated in double-glazed window units, a thickness of each window unit cannot but be increased.